A communication system employing a non-contact IC card is used for automatic ticket-gates of ski lifts, railroads and the like, automatic freight-sorting, and the like. FIG. 15 is a perspective view showing one example of a conventional non-contact IC card. An IC card 2 shown in FIG. 15 is a 1-coil IC card comprised of a coil 4 used as an antenna, capacitors C1 and C2, and an IC chip 8.
Capacitors C1, C2 and IC chip 8 are mounted to a synthetic resin substrate in the form of a film. The substrate with capacitors C1, C2 and IC chip 8 mounted thereto is referred to as a tape automated bonding (tab) 10.
FIG. 16A is a cross section of the FIG. 15 IC card 2 taken along line S1—S1. In the figure, a core member 12 of synthetic resin is sandwiched by paired surface members 14 and 16. Tab 10 with capacitors C1, C2 and IC chip 8 mounted thereto is fixed to surface member 14 exposed in a cavity 18 provided in core member 12. A joint of tab 10 and IC chip 8 is covered with a sealing agent 9 such as epoxy resin. Coil 4 is arranged between surface member 14 and core member 12. Coil 4 and tab 10 are connected together via a wire 20.
FIG. 16B is a circuit diagram of IC card 2. Referring to the figure, in IC card 2 an electromagnetic wave sent from a reader/writer (an interrogator (not shown)) is received at a resonator circuit 22 configured of coil 4 and capacitor C1 and it is used as a power supply. It should be noted that capacitor C2 is a power smoothing capacitor.
Furthermore, information superimposed on the electromagnetic wave and thus sent therewith is decrypted by a control unit (not shown) provided in IC chip 8. The control unit then rewrites a content of a non-volatile memory (not shown) provided in IC chip 8, makes a response to the reader/writer, and the like. The response is made by varying an impedance of resonator circuit 22. The reader/write obtains the content of the response by detecting an impedance variation (an impedance reflection) of its resonator circuit (not shown) that is associated with the impedance variation of IC card 2 resonator circuit 22.
As such, IC card 2 does not require an internal power supply and also allows non-contact communication of data.
However, conventional IC card 2 has the following disadvantage: in conventional IC card 2, a pad (or a terminal) (not shown) used for checking the performance of a mounted non-volatile memory or the like in the process for manufacturing the same is provided on a surface of IC chip 8. As such, the pad is exposed when surface members 14, 16 are removed. By applying a probe (an inspecting needle) on the exposed pad, the data in the non-volatile memory can readily be read and IC chip 8 can be operated. That is, the conventional IC card does not have high data security. Furthermore, as shown in FIG. 17, there is also an IC card which mounts to tab 10 two IC chips, i.e., an IC chip 6 with a control unit (not shown) and an IC chip 7 with a non-volatile memory (not shown). In such a type of IC card, in addition to the pad mentioned above a wire 24 connecting two IC chips 6 and 7 together is also exposed, which further facilitates reading the data stored in the non-volatile memory.
The present invention has been made to overcome the above disadvantages and contemplates an IC card and IC chip module with enhanced data security.